Reflective road markers, commonly known as cat's eyes, are used worldwide to manage traffic and maintain road safety. These markers generally include reflective material, visible both during the day and at night on exposure to light from street lamps or vehicle headlights. Road markers are widely used as they are inexpensive to produce, simple to install and need little or no maintenance yet still perform a very helpful function for motorists. While reflective road markers may be effective in managing traffic, they do not assist motorists in assessing ambient temperature and the effect of ambient temperature on driving conditions.
Driving conditions can be hazardous in the presence of ice and, in particular, black ice. Black ice is generally known as a thin coating of glazed ice on a road or sidewalk that is transparent and, thus, may not be seen. Black ice lacks noticeable ice pellets, snow or sleet to indicate that road conditions are dangerous and that driving speed should be reduced. Bridges and overpasses may be especially hazardous, as black ice forms first on these structures due to a cooling flow of air both above and beneath the structures.
It should be appreciated that it may be useful to have a cat's eye device that serves the dual purpose of being a reflective road marker and which alerts drivers to potential safety hazards associated with ambient temperature such as ice formation.
One existing technology relating to illuminating road markers powered by solar cells may be referred to as a solar road stud as described in US2011135386A1. These markers or studs flash constantly to alert drivers to dangerous sections of road or hazardous conditions. One drawback of these existing solar road studs is that the flashing lights do not automatically switch on and off depending on changes in the conditions. They must also be activated remotely. Thus, they are useful solely on sections of road that are always hazardous to drive and which are able to be monitored, rather than on sections of road that are intermittently hazardous and/or sections that are remote from monitoring sites.
Other existing technology overcomes the problem of controlling the illumination of road markers or signs by linking them to road condition sensors and to a network or data transmission system. The network may automatically control warning signals to drivers or require remote control. A drawback of those systems is that they are expensive and complex to install, operate, maintain and repair and, hence, may be prohibitively costly to implement. They also lack flexibility in location as they must be installed proximate an external data collection point.
One patent publication JP2002-256520 proposes an alternative solution describing a road marker that continuously illuminates alternating between colours depending on the temperature. Continuous illumination in this manner is not ideal as it means parts wear out and energy use is higher than may be needed. In addition, the device described does not recognise issues surrounding rapid on-off cycling that can occur thereby resulting in problems with longevity of the circuitry and device as a whole.